Search results for "Particles"
showing 10 items of 8085 documents
Features of magnetorheology of biocompatible chain-forming ferrofluids with multi-core magnetic nanoparticles: Experiment and simulation
2020
Abstract We study the magnetorheological properties and structural transitions in novel aqueous colloidal suspensions of magnetic nanoparticles developed for biomedical applications. Defined-shape field-tunable superparamagnetic nanoparticles with clustered cores and their suspensions are produced. The region of intermediate magnetic coupling strength between colloidal ferrofluids and magnetorheological suspensions is systematically studied for the first time. Hybrid numerical simulations with hydrodynamic interactions provide full structural information. The distinctive features of the rheograms are related to transitions between Brownian and persistent microstructure, shape anisotropy, co…
High field magnetization of the colloidal Mn–Zn ferrite
1999
Abstract The magnetic properties of a hydrocarbon based colloid (stabilized by oleic acid) of polydisperse chemically co-precipitated Mn 0.5 Zn 0.5 Fe 2 O 4 particles are discussed in the paper. Two fractions are separated from an initial ferrofluid sample by centrifugation. X-ray diffraction measurements show the crystal structure of the particles and a broadened shape of the diffraction lines. Mean particle diameters 6.2 nm (the light fraction) and 9.7 nm (the heavy one) were determined by TEM measurements. The magnetization of the colloids is measured by VSM up to 12 T. A significant slope in the magnetization curves in the high field region is displayed for both samples in the temperatu…
Magnetically enhancing the Seebeck coefficient in ferrofluids.
2019
The influence of the magnetic field on the Seebeck coefficient (Se) was investigated in dilute magnetic nanofluids (ferrofluids) composed of maghemite magnetic nanoparticles dispersed in dimethyl-sulfoxide (DMSO). A 25% increase in the Se value was found when the external magnetic field was applied perpendicularly to the temperature gradient, reminiscent of an increase in the Soret coefficient (ST, concentration gradient) observed in the same fluids. In-depth analysis of experimental data, however, revealed that different mechanisms are responsible for the observed magneto-thermoelectric and -thermodiffusive phenomena. Possible physical and physico-chemical origins leading to the enhancemen…
Non-isothermal mass transfer of ferrocolloids through porous membrane
2011
Abstract The present paper deals with transport properties of ferrofluid nanoparticles in non-isothermal capillary-porous layer. Experiment establishes that the temperature difference, which is applied across the layer, induces a thermoosmotic pressure gradient directed toward increasing temperature. The measurement results are interpreted in a frame of phenomenology of linear irreversible thermodynamics. The transport coefficients are evaluated comparing the measured separation curves with approximate solution of the corresponding mass transfer problem.
Large-N kinetic theory for highly occupied systems
2018
We consider an effective kinetic description for quantum many-body systems, which is not based on a weak-coupling or diluteness expansion. Instead, it employs an expansion in the number of field components N of the underlying scalar quantum field theory. Extending previous studies, we demonstrate that the large-N kinetic theory at next-to-leading order is able to describe important aspects of highly occupied systems, which are beyond standard perturbative kinetic approaches. We analyze the underlying quasiparticle dynamics by computing the effective scattering matrix elements analytically and solve numerically the large-N kinetic equation for a highly occupied system far from equilibrium. T…
Shape transitions of giant liposomes induced by an anisotropic spontaneous curvature
2000
International audience; We explore how a magnetic field breaks the symmetry of an initially spherical giant liposome filled with a magnetic colloid. The condition of rotational symmetry along the field axis leads either to a prolate or to an oblate ellipsoid. We demonstrate that an electrostatic interaction between the nanoparticles and the membrane triggers the shape transition. PACS numbers: 75.
The performance of the ATHENA X-ray Integral Field Unit
2018
The X-ray Integral Field Unit (X-IFU) is a next generation microcalorimeter planned for launch onboard the Athena observatory. Operating a matrix of 3840 superconducting Transition Edge Sensors at 90 mK, it will provide unprecedented spectro-imaging capabilities (2.5 eV resolution, for a field of view of 5') in the soft X-ray band (0.2 up to 12 keV), enabling breakthrough science. The definition of the instrument evolved along the phase A study and we present here an overview of its predicted performances and their modeling, illustrating how the design of the X-IFU meets its top-level scientific requirements. This article notably covers the energy resolution, count-rate capability, quantum …
Linear Response Theory with finite-range interactions
2021
International audience; This review focuses on the calculation of infinite nuclear matter response functions using phenomenological finite-range interactions, equipped or not with tensor terms. These include Gogny and Nakada families, which are commonly used in the literature. Because of the finite-range, the main technical difficulty stems from the exchange terms of the particle–hole interaction. We first present results based on the so-called Landau and Landau-like approximations of the particle–hole interaction. Then, we review two methods which in principle provide numerically exact response functions. The first one is based on a multipolar expansion of both the particle–hole interactio…
Gas phase synthesis of 4d transition metal carbonyl complexes with thermalized fission fragments in single-atom reactions
2021
Abstract The formation of carbonyl complexes using atom-at-a-time quantities of short-lived transition metals from fusion and fission reactions was reported in 2012. Numerous studies focussing on this chemical system, which is also applicable for the superheavy elements followed. We report on a novel two-chamber approach for the synthesis of such complexes that allows spatial decoupling of thermalization and gas-phase carbonyl complex synthesis. Neutron induced fission on 235U and spontaneous fission of 248Cm were employed for the production of the fission products. These were stopped inside a gas volume behind the target and flushed with an inert-gas flow into a second chamber. This was fl…
Measurements of isomeric yield ratios of fission products from proton-induced fission on natU and 232Th via direct ion counting
2017
Independent isomeric yield ratios (IYR) of 81Ge, 96Y, 97Y, 97Nb, 128Sn and 130Sn have been determined in the 25 MeV proton-induced fission of natU and 232Th. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyväskylä. A direct ion counting measurement of the isomeric fission yield ratios was accomplished for the first time, registering the fission products in less than a second after their production. In addition, the IYRs of natU were measured by means of γ-spectroscopy in order to verify the consistency of the recently upgraded experimental setup. From the obtained results, indications of a dependence of the production rate …